The present invention relates to a separator for removing entrained particles from a gas stream and specifically relates to an oil separator for removing oil, moisture and other contaminants from a stream of compressed air.
Many types of air compressor systems, particularly those having rotors or screws, use large amounts of oil. The oil is typically injected into the compressor housing for a number of reasons including cooling the air compressor system, lubricating the bearings, balancing axial forces and sealing the rotors. Although using oil is essential for operating these particular types of systems, the oil must be removed from the stream of compressed air before the product may be used downstream for pneumatic equipment and/or other tools.
In certain prior art embodiments, oil separators include a first unit which serves as an oil reservoir, a second unit which functions as a cyclonic separator and finally a third unit including a demister or filter through which compressed air is conducted to remove any residual oil. These several units are generally arranged in a serial configuration which requires complex couplings and piping occupying considerable space.
Commonly assigned U.S. Pat. No. 4,092,137, the disclosure which is hereby incorporated by reference herein, discloses a separating system in which all of the constituent elements (i.e. the oil reservoir, the cyclonic separator and the filter) are combined in one single unit. Specifically, the '137 patent discloses a substantially L-shaped tank which includes both a vertical housing including a liquid-reservoir and a horizontal housing including a filter through which compressed gas, having liquid entrained therein, is conducted. The compressed gas is initially guided along a centrifugal path through the vertical housing for separating the liquid from the gas and is then passed through a filter within the horizontal housing for removing any additional fluid remaining in the compressed gas.
FIG. 1 shows a typical prior art oil separator system 10 having an inlet 12 for introducing an air/oil mixture into the separator 10 and a replaceable filter 14 which is secured adjacent a top portion 16 thereof. The air/oil mixture is directed toward a bottom 18 of the filter 14. In operation, the air/oil mixture strikes the bottom surface 18 of the filter element whereupon the compressed air passes through the filter and towards an outlet 20. However, the oil in the air/oil mixture is not able to pass through the filter 14 and drops toward an oil collecting reservoir located at a lower end 22 of the separator tank 10. The oil 24 in the reservoir is then removed from the separator tank 10 through an oil outlet 26. Although the oil separator shown in FIG. 1 has proven to be somewhat successful in removing oil from an air/oil mixture, there are many problems associated with this particular design. Specifically, the design requires the use of a separate, expensive oil filter element which must be replaced and/or maintained on a regular basis. In addition, the filter comprises a very dense media which results in a high pressure drop in the compressed air as the air passes through the filter. As a result, the overall efficiency of the compressor system is reduced. The filter media generally includes a multi-layered interface, such as a sheet of paper having multiple layers, which allows the compressed air, but not the oil, to pass through. As a result, after a few hours of operating the system the multi-layered interface typically becomes saturated with oil, a situation which degrades the performance of the filter. This results in a significant pressure drop because the compressed air has a more difficult time moving through the oil saturated interface of the filter. Yet another problem exists with smaller oil separating elements wherein the air velocity through the small separators is too high to provide good air/oil separation. As a result, there is a need for a small oil separator which is capable of reducing the velocity of the air stream to a level sufficient for removing an adequate amount of oil from the air/oil mixture.
The present invention overcomes the above-mentioned problems by providing a separator element which does not require an expensive filter which must be continually replaced and/or maintained on a regular basis. The present invention also provides a small separator tank (i.e. a tank having an outer diameter of six inches or less) which is capable of reducing the velocity of the air stream in the tank to an acceptable level. The present invention also provides a separator tank having a barrier layer which isolates oil separated from a gas/oil mixture so that the separated oil is not repeatedly exposed to the gas/oil mixture flowing through the tank. Thus, the barrier layer allows the separated oil to collect in an oil storage area in a lower chamber of the separator tank without allowing significant air movement within the oil storage area.